Quadrajet Carb Question

Old May 23rd, 2019, 05:11 AM
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Quadrajet Carb Question

Hello out there. Have a 1986 442. I've had now 4 Cutlasses, 2 - 1979 Hurst Olds - after years of collecting AMC vehicles and really like them a lot. At 55 years of age I'm still no mechanic for sure.
My question is this - There is a plug that goes into the carburetor, (blue) at the top and has a plug in with wires that connects into it. The car runs rough as you know what and when I unplug it - it'll run great - HOWEVER only when it is warmed up.
When it is unplugged - it'll take 5 minutes of keeping the car running to warm up until it finally smooths out.
Obviously the problem is in this plug, I'm sure it is some sort of sensor.
What is this sensor called???????????? I think I can replace it myself if I take my time.
Thanks, Cory

Last edited by firstoldsmobile; May 23rd, 2019 at 05:14 AM.
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Old May 23rd, 2019, 06:29 AM
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It's a mixture control solenoid driven by the computer.
While I haven't messed with that new-fangled-stuff, I would first do a basic rebuild on the carb to make sure the solenoid moves freely, then check all the wiring. The computer will use the coolant temp and a few other things to drive that solenoid.
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Old May 23rd, 2019, 03:11 PM
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By unplugging the MC solenoid on a Computer Command Control CCC carb it is going into full rich mode indicating that the roughness may be from a lean condition such as a vacuum leak. Im guessing from far away that the MC solenoid isn't the problem. With the key in the run position can you hear theMC solenoid clicking/cycling/chattering? The CCC Quadrajet is a good carb but a little complicated to set-up; however, when set-up and dialed in they run very well. I suggest reading up on them a lot and if you aren't totally comfortable with it that you find someone who was a GM tech/mechanic in the 80-90's to work on it.

Best of luck!!!
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